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selection sort
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selection sort
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Selection sort is a sorting technique whose main idea is to select the smallest element in the unsorted array repeatedly.
The smallest element of unsorted array selected is swapped with the first element of the unsorted array.
If there are n elements then the array can be sorted in n-1 passes.
In each pass, the smallest element of unsorted array is exchanged with first element of unsorted array.
The selection sort algorithm sorts an array by repeatedly finding the minimum element (considering ascending order) from unsorted part and putting it at the beginning. The algorithm maintains two subarrays in a given array.
1) The subarray which is already sorted.
2) Remaining subarray which is unsorted.
In every iteration of selection sort, the minimum element (considering ascending order) from the unsorted subarray is picked and moved to the sorted subarray.
For example,
arr[] = 64 25 12 22 11
// Find the minimum element in arr[0...4]
// and place it at beginning
11 25 12 22 64
// Find the minimum element in arr[1...4]
// and place it at beginning of arr[1...4]
11 12 25 22 64
// Find the minimum element in arr[2...4]
// and place it at beginning of arr[2...4]
11 12 22 25 64
// Find the minimum element in arr[3...4]
// and place it at beginning of arr[3...4]
11 12 22 25 64
// C program for implementation of selection sort
#include <stdio.h>
void swap(int *xp, int *yp)
{
int temp = *xp;
*xp = *yp;
*yp = temp;
}
void selectionSort(int arr[], int n)
{
int i, j, min_idx;
// One by one move boundary of unsorted subarray
for (i = 0; i < n-1; i++)
{
// Find the minimum element in unsorted array
min_idx = i;
for (j = i+1; j < n; j++)
if (arr[j] < arr[min_idx])
min_idx = j;
// Swap the found minimum element with the first element
swap(&arr[min_idx], &arr[i]);
}
}
/* Function to print an array */
void printArray(int arr[], int size)
{
int i;
for (i=0; i < size; i++)
printf("%d ", arr[i]);
printf("\n");
}
// Driver program to test above functions
int main()
{
int arr[] = {64, 25, 12, 22, 11};
int n = sizeof(arr)/sizeof(arr[0]);
selectionSort(arr, n);
printf("Sorted array: \n");
printArray(arr, n);
return 0;
}